Wood processing mills all over the world convert some form of forest raw material (e.g., wood logs, chips, sawdust, biomass) into a finished product (e.g., wood pulp, paper, timber, fiber boards, energy). In most cases, these raw materials arrive at the mill on some form of vehicle—typically trucks, but also trains and water vessels. Most of the time it is important to measure the quantity (and perhaps other parameters) of these raw materials as they arrive at the mill, including for payment, inventory, accounting and/or other purposes.
To determine the quantity of raw material in a given delivery, various methods can be used, primarily relating to either weight or volume. Weight measurement is typically used for its convenience and simplicity, but has a significant limitation when the density of the measured material is uncertain. For example, forest raw materials can have greatly variable densities not only due to their biological composition, but also due to the varying degree of moisture they hold. A freshly cut log can have twice the moisture content of one that has been drying for six weeks. Volumetric measurement removes the problem of variable density from the equation, but it can be very difficult to measure the volume of highly heterogeneous materials that arrive at wood processing mills in an automatic and repeatable manner.
In the lumber industry, large diameter logs (typically about 7-30 inches) often arrive at a saw mill loaded on trucks (or other vehicles) and are then sawn and processed into finished lumber. In the Southeast United States, which has a significant amount of the country's lumber industry, logs are usually delivered by logging trucks and are weight-scaled at the mill gate. Some mills include additional controls, such as counting logs and looking for “defects,” that are usually done visually by an on-site operator. Visual inspection typically requires the operator to walk around the truck looking for different defects, sometimes having to climb onto the truck to gain better visual access to some logs. This represents a safety hazard and can consume quite a bit of time, during which the truck remains stationary. Some mills choose (or are required by law) to hire large teams of human scalers that select random trucks to be hand-scaled, log-by-log, in a meticulous and time-consuming process that involves unloading every log to the ground. All these processes are constrained by time and cost. Furthermore, the additional movement of logs (from truck to ground and ground to log yard) adds machinery cost, requires large amounts of space in the mill, and increases log breakage due to additional log handling.
Sawmills are usually most interested in the total useful volume of a given log (often measured in “cubic board feet”), since this indicates how much finished lumber can be produced from that log. Weight alone is often an incomplete variable, since weight for a given volume can vary significantly depending on density and moisture content. Furthermore, sawmills tend to assign higher value to larger diameter logs as higher value-added products can be made from these (e.g., a high diameter log allows for the production of many combinations of different products, whereas small diameter logs can only be used to produce small products). Sawmills may also penalize for defects in logs that take away from the useful volume, such as crookedness, cracks, splits, rot, knots and others.
Accordingly, there is a need for a system that automatically and precisely estimates desired variables of loads delivered to a mill to improve the efficiency of the mill by a significant margin in terms of time and cost. There is also a need for a system that aids a human operator in rapidly detecting and registering specific log defects in a much more time and cost efficient manner, thus increasing the mill's capability of searching for defects and/or reducing the need for additional people. It is also desirable that this system provides the capability of storing images of each load that is scanned, as well as the inputs of the human operator.